Investigations will be continued on the mechanism of action of ethanolamine ammonia-lyase, and adenosylcobalamin-dependent enzyme. Analogs of the substrate will be tested for their effect on the enzyme-cofactor complex. An analog of the cofactor will be examined to test the hypothesis that transalkylation of the cobalt participates in the catalytic process. Experiments with ESR spectroscopy will be conducted to provide further information regarding enzyme-catalyzed homolysis of the carbon-cobalt bond, a step previously shown to be involved in catalysis, and the interaction between enzyme and omega-adenylalkyl cobalamins will be studied to test the hypothesis that the enzyme facilitates homolysis of the carbon-cobalt bond by stretching the bond. Hydrogen transfer will be further investigated by experiments designed to determine the origin of an unusually high tritium isotope effect observed in this reaction. Attempts will be made to inactivate the enzyme and label the active site by means of affinity labels as well as non-specific inactivating agents. The stereochemistry of the rearrangement will be investigated using stereospecifically labelled ethanolamine and propanolamine as substrates. Structural studies will be undertaken to further define the quaternary structure of the enzyme and to investigate the roles of the various subunits in the catalytic process.